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Polyfluorinated aryl imines 2,4,5-R1,R2,R3-C6H2-HC=N-1-C10H7 (R1 = F, R2 = F, R3 = H (1); R1 = F, R2 = H, R3 = F (2) and R1 = F, R2 = F, R3 = F (3)) and F5C6-HC=N-1-C10H7 (7) reacted with CoMe(PMe3)4 to give rise to hydrido [CNC]-pincer cobalt(iii) complexes (2,4,5-R1,R2,R3-C6H-HC=N-1-C10H6)Co(H)(PMe3)2 (R1 = F, R2 = F, R3 = H (4); R1 = F, R2 = H, R3 = F (5); R1 = F, R2 = F, R3 = F (6)) and (F4C6-HC=N-1-C10H6)Co(H)(PMe3)2 (8) via selective C–F/C–H bond activation. Penta-coordinate dicarbonyl cobalt(i) complexes (2,4,5-R1,R2,R3-C6H-HC=N-1-C10H7)Co(CO)2(PMe3) (R1 = F, R2 = H, R3 = F (9); R1 = F, R2 = F, R3 = F (10)) were obtained from reactions of hexa-coordinate cobalt(iii) complexes 5 and 6 with carbon monoxide through reductive elimination. Cobalt(iii) halides (2,4,5-R1,R2,R3-C6H-HC=N-1-C10H6)Co(i)(PMe3)2 (R1 = F, R2 = F, R3 = H (11); R1 = F, R2 = H, R3 = F (12); R1 = F, R2 = F, R3 = F (13)) and (2,4,5-R1,R2,R3-C6H-HC=N-1-C10H6)Co(Br)(PMe3)2 (R1 = F, R2 = F, R3 = H (14); R1 = F, R2 = H, R3 = F (15); R1 = F, R2 = F, R3 = F (16)) were prepared by the interaction between hydrido cobalt(iii) complexes 4–6 and MeI or EtBr. The molecular configurations of complexes 4, 8, and 11 were determined by single crystal X-ray diffraction. We then confirmed that the four hydrido cobalt(iii) complexes 4–6 and 8 could be used as catalysts for reduction of aldehydes and ketones. Complex 8 is the best catalyst among the four complexes and can selectively catalyze the carbonyl groups of α,β-unsaturated aldehydes and ketones. [ABSTRACT FROM AUTHOR]

Two novel cobalt Schiff base complexes 3 and 4, ((2-PPh2)C6H4)C=N(C10H7)Co(PMe3)2 (3) and ((2-PPh2)C6H4)CH=N(C6H5)Co(PMe3)2 (4) with η2(C–H) coordination, were synthesized by the reactions of Schiff base preligands ((2-PPh2)C6H4)CH=N(C10H7) (1) and ((2-PPh2)C6H4)CH=N(C6H5) (2) with CoMe(PMe3)4via sp2 C–H bond activation. Under similar reaction conditions, the reactions of Co(PMe3)4 with 1 and 2 gave rise to the simple π-(C=N)-coordinated cobalt(0) complexes ((2-PPh2)C6H4)CH=N(C10H7)Co(PMe3)2 (5) and ((2-PPh2)C6H4)CH=N(C6H5)Co(PMe3)2 (6). Complex ((2-PPh2)C6H4)C=N(C10H6)CoI(PMe3)2 (7) was obtained through the reaction of 3 with iodomethane via the activation of the second C–H bond in 1. The substitution reaction of complex 3 with carbon monoxide afforded the dicarbonyl cobalt(i) complex ((2-PPh2)C6H4)C=N(C10H7)Co(CO)2(PMe3) (8). The molecular structures of 4, 5, 7 and 8 were determined by single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]